The invention provides an industrialized production method for high-purity decitabine. The method comprises the following steps of: 1, performing silanization reaction of 5-azacytosine, bis(trimethylsilyl)amine and trimethyl chlorosilane, which serve as raw materials, to prepare 2,4-bis(trimethylsilyl)-5-azacytosine; 2, performing reaction of the product obtained by the step 1 and 1-chloro-3,5-bis-(4-chlorobenzoyl)-2-deoxy-D-ribofuranose, which serve as raw materials, to prepare a crude product of 1-(3,5-bis-(4-chlorobenzoyl)-2-deoxy-beta-D-ribofuranose)-5-azacytosine; 3, dissolving the product obtained by the step 2 in a C5 to C7 hydrocarbon, stirring, filtering and drying to obtain a refined product; and 4, producing the high-purity decitabine by using the product obtained by the step 3, methyl alcohol and sodium methoxide as raw materials. The method overcomes the disadvantages of need of column purification, low purity, difficult industrial production in the prior art, and has the advantages of simple and convenient operation, small solvent consumption, small influence on the environment, low labor intensity, short period, high product purity, single impurity and less than 0.1 percent total impurity content.